Alkylated diamines have been known for a substantial period of time and find use in the preparation of polyurethane elastomers. The diamines are typically used in that form as chain extenders for polyurethanes, i.e., forming a short chain urea linkage to strengthen the elastomer. As is known, the alkyl group alters the reactivity of the amine thus giving the composition unique processing properties for producing polyurethane elastomers.
A secondary use for the alkylated diamine products is in the manufacture of diisocyanates which are also suited for the synthesis of polyurethane elastomers. They can also be used for plasticizers, or as intermediates for the manufacture of pesticides and alkyd resin modifiers.
Two types of synthesis techniques have been used to produce alkylated aromatic amines, such as, an alkylated toluenediamine. One of the earliest techniques used to prepare an alkylated aromatic diamine employed a Freidel-Crafts alkylation of an aromatic hydrocarbon, then dinitration of the alkylated aromatic hydrocarbon followed by reduction of the nitro groups to amine groups. The diamine could be converted to the diisocyanate by reaction with phosgene. Another technique for producing an alkylated aromatic amine involved nitration of an aromatic hydrocarbon, followed by reduction to the amine and then alkylation of the amine.
Representative patents illustrating various alkyl aromatic diamines and derivatives thereof are as follows:
U.S. Pat. Nos. 3,428,610 and 4,218,543 disclose the use of alkylated toluenediamines in the manufacture of polyurethane resins with the '543 patent showing its use in RIM manufacturing techniques. Alkylated diamines include 1-methyl-3,5-diethylpheylene-2,4-diamine and 1,3,5-trimethylphenylene-2,4-diamine. The diethyltoluenediamine derivative is best known and is referred to as diethyl TDA or DETDA and is probably the most widely used alkylated aromatic diamine for RIM manufacture.
U.S. Pat. No. 4,440,952 shows the synthesis of 1-methyl-2,4-diamino-5-isopropylbenzene and 1-methyl-2,6-diamino-3-isopropylbenzene and the use of the 2,6-isomer as a chain extender for polyurethanes.
European Pat. No. 0069286 discloses various alkyl-substituted phenylenediamines as chain extenders for the production of polyurethanes by reaction injection molding techniques. Some of the compositions suggested as being suited for such use include the 1,3-dimethyl-5-tert-butyl-2,6-diaminobenzene, 2-methyl-4,6-di-tert-butyl-1,3-diaminobenzene, 1,3-dimethyl-5-tert-amyl-2,4-diaminobenzene or its equivalent.
U.S. Pat. No. 4,529,746 discloses the synthesis of C.sub.1-4 alkylated vicinal toluenediamines and their use as extenders for the preparation of polyurethane-polymer elastomers. The example shows an ethylated vicinal toluenediamine.
Aromatic compositions having unsaturated organo substituents are known and have been prepared by alkylation of aromatic compositions with diolefins. Some patents which show the manufacture of aromatic compositions having unsaturated organo substituents include:
U.S. Pat. No. 2,403,963 which discloses the reaction of benzene and butadiene in the presence of a boron trifluoride catalyst. Phenylbutenes are produced.
U.S. Pat. No. 2,471,922 discloses that aromatic hydrocarbons, which include phenols and aromatic halides, can be reacted with 1,3-diolefins to produce alkenyl derivatives. Examples of low-boiling 1,3-diolefins which can be used in the alkenylation include 1,3-butadiene, 1,3-pentadiene and so forth. Catalyst systems included boron trifluoride and boron trifluoride-phosphoric acid systems.
U.S. Pat. No. 3,865,889 discloses the preparation of an alkenylated aromatic hydrocarbon such as those obtained by reacting butadiene with an alkylbenzene, e.g., toluene or xylene. An alkali metal promoter is used to catalyze the reaction.
U.S. Pat. No. 2,843,565 discloses the production of butenyl-phenol-aldehyde resins which involves the reaction of an alkenylphenol; with formaldehyde. Conjugated dienes such as piperylene, cyclopentadiene, 1-chloro-2-methyl-butadiene are reacted with phenols in the presence of phosphoric acid catalyst and the reaction product then reacted with formaldehyde.
West German Pat. No. 1,079,628 discloses the preparation of cyclopentenyl-substituted aromatic amines by reacting cyclopentadiene at elevated temperature in the presence of bleaching earth with primary, secondary or tertiary aromatic amine substrates. Aniline, N-methylaniline, chloroaniline, and phenylenediamine are suggested candidates.
European Pat. No. 0082258 discloses various meta-phenylenediamines having one or two benzyl rings having lower reactivity due to steric hindrance. Steric hindrance is effected through the use of an aromatic substituent which also may be substituted with various groupings. An example of an amine is 4,6-bis (.alpha.,.alpha. dimethylbenzyl)-1,3-phenylenediamine prepared by reacting 2-methylstyrene with meta-phenylenediamine.